Apparatus and method for detection and discrimination molecular object

Abstract

An apparatus for detecting an object capable of emitting light. The apparatus comprises a light detector comprising at least two optical sensors capable of determining the intensity of the light; and a computer processing output signal generated by the optical sensors and comparing a result of the processing with a known result corresponding to a known type to determine whether the object belongs to the known type.

What is claimed is: 
     
       1. A method of sequencing a nucleic acid, comprising the steps of:
 (a) performing single molecule nucleic acid sequencing of at least one nucleic acid molecule, wherein the single molecule nucleic acid sequencing leads to emission of light correlated to the identity of at least one base comprised by the nucleic acid; 
 (b) detecting the light with at least one light detector comprising a multi-junction photodiode which includes at least a first optical sensor configured to generate a first output signal in response to the light and a second optical sensor configured to generate a second output signal in response to the light; 
 wherein the first optical sensor comprises a first semiconductor material and the second optical sensor comprises a second semiconductor material different from the first semiconductor material, and the first and second optical sensors have different responsive properties; 
 (c) processing the first and second output signals by summing the first and second output signals to obtain a total signal, dividing the second output signal by the total signal to obtain a first ratio, and dividing the first output signal by the second output signal to obtain a second ratio; and 
 (d) comparing the first ratio with a first known ratio range corresponding to a known type of nucleic acid base; 
 (e) confirming the known type of nucleic acid base by comparing the second ratio to a second known ratio range corresponding to the known type of nucleic acid base; and 
 (f) determining the type of nucleic acid base when the first ratio corresponds to the first known ratio range and the second ratio corresponds to the second known ratio range. 
 
     
     
       2. The method of  claim 1 , wherein the first optical sensor includes a first p-n junction and the second optical sensor includes a second p-n junction. 
     
     
       3. The method of  claim 2 , wherein the first p-n junction and second p-n junction are within one device. 
     
     
       4. The method of  claim 1 , further comprising collecting and directing the light emitted from the nucleic acid molecule to the optical sensors with an optical structure. 
     
     
       5. The method of  claim 4 , wherein the optical structure comprises a prism. 
     
     
       6. The method of  claim 4 , wherein the optical structure comprises a grating. 
     
     
       7. The method of  claim 4 , wherein the optical structure comprises a lens. 
     
     
       8. The method of  claim 4 , wherein the optical structure comprises an optical filter. 
     
     
       9. The method of  claim 1 , wherein the at least first and second optical sensors are stacked. 
     
     
       10. The method of  claim 1 , wherein the at least two optical sensors are arranged horizontally. 
     
     
       11. The method of  claim 1 , wherein the light detector further comprises a circuit of signal amplifier, A/D convertor, integrator, comparator, logic circuit, readout circuit, memory, microprocessor, clock, and/or address. 
     
     
       12. The method of  claim 1 , wherein the nucleic acid molecule is labeled with at least one object having light emitting capability. 
     
     
       13. The method of  claim 12 , wherein the object is chosen from at least one quantum dot, at least one fluorescent protein, and at least one fluorescent small chemical moiety. 
     
     
       14. The method of  claim 1 , wherein the nucleic acid molecule is fluorescently labeled. 
     
     
       15. The method of  claim 1 , further comprising detecting a plurality of nucleic acid molecules using the at least one light detector, wherein the plurality of nucleic acid molecules are comprised by a liquid suspension, which flows past the at least one light detector.